BS EN IEC 61158-4-12:2019 Industrial communication networks. Fieldbus specifications Data-link layer protocol specification. Type 12 elements

Automatic control systems
Process control
Bus networks
Industrial
Interfaces (data processing)
Data transmission
Fieldbus
Communication networks
Communication procedures
Data link layer (OSI)
Computer networks
Open systems interconnection

Link: BS EN IEC 61158-4-12:2019 Industrial communication networks. Fieldbus specifications Data-link layer protocol specification. Type 12 elements
Source: BSI Standards